The objective of the Molecular, Cellular and Structural Biology (MCSB) training program is to provide predoctoral students with the knowledge to become skilled experimentalists, effective communicators, and creative thinkers. The training program offers a multidisciplinary course of study leading to the Ph.D. degree and provides students with the opportunity to select one of two programs: Molecular and Cellular Biology or Biochemistry and Structural Biology. Within the Molecular and Cellular Biology Program students additionally specialize either in Biochemistry and Molecular Biology, or Developmental Biology, or Immunology and Pathology. During the first year students enroll in three out of four core courses, Biochemistry, Molecular Genetics, Cell Biology and Structural Biology. Students also initially receive training to critically evaluate and present original research articles in Journal Club, while in subsequent years they orally present their own research. Students gain valuable insights into teaching by serving as teaching assistants for undergraduate classes in the second semester of the first year and the first semester of the second year. Laboratory training experiences, or rotations, which continue throughout their first academic year help the student to select a mentor for his/her thesis research at the end of the first year. After three semesters the students are required to pass a written qualifying exam followed by the preparation of a proposal on their intended research project and the defense of this proposal before a faculty committee. Following successful defense of the proposal, students advance to candidacy and the faculty thesis committee annually monitors the students'progress until successful completion of the project and defense of a written doctoral thesis. In addition, the students present yearly reports on their research progress in a seminar forum to other graduate students, postdoctoral fellows, and faculty. The MCSB training program crosses departmental and institutional boundaries to offer thesis research training in 72 different mentored laboratories at three institutions: Stony Brook University, Brookhaven National Laboratory, and Cold Spring Harbor Laboratory. There are currently 146 students in the program with approximately 25 admissions per year. The top four students in their second and third years will be selected by the Executive Committee as NIH predoctoral trainees on the basis of their first year performance also taking into account their undergraduate achievements.